Diesel Exhaust and Mechanism of Asthma

September 27, 2017 updated by: Christopher Carlsten, University of British Columbia

Effects of Diesel Exhaust on Airways

This experiment is designed to test the hypothesis that oxidative stress is responsible for changes in airway responsiveness in humans exposed to diesel exhaust.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

The specific aim is to test the hypothesis that diesel exhaust (DE) increases airway reactivity via oxidative stress, particularly in asthmatics. To test this hypothesis, we use a crossover in vivo experimental model in mild asthmatics and normal controls using a state-of-the-art diesel exhaust exposure facility.

Participants took N-acetylcysteine (600 mg) or placebo capsules three times daily for six days. On the final morning of supplementation, participants were exposed for 2 hours to either filtered air or diesel exhaust (300 µg·m-3 of particulate matter smaller than 2.5 microns). Twenty-six non-smokers between 19-49 years were studied under three experimental conditions (filtered air with placebo, diesel exhaust with placebo and diesel exhaust with N-acetylcysteine) using randomized, double-blind, crossover design, with a two week minimum washout between conditions. Methacholine challenge was performed pre-exposure (to determine baseline airway responsiveness) and post-exposure (to determine the effect of exposure).

Study Type

Interventional

Enrollment (Actual)

26

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Canada
    • British Columbia
      • Vancouver, British Columbia, Canada, V5Z1M9
        • University of British Columbia

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

19 years to 49 years (Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Between 19-49 years, non smokers, asthmatics, healthy controls

Exclusion Criteria:

  • Smokers, pregnant or co-existing medical condition for which diesel exhaust would confer significant risk (i.e. coronary artery disease)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Triple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Placebo Comparator: Filtered air with placebo
Exposure for 2 hours to filtered air and placebo tablets 3 times daily for 6 days
Other: Filtered air
A placebo tablet taken 3 times daily for 6 days prior to exposure to filtered air for 2 hours. The last supplement was taken the morning of the exposure
Active Comparator: Diesel exhaust with placebo
Exposure for 2 hours to diesel exhaust and placebo tablets 3 times daily for 6 days
Other: Diesel exhaust
A placebo tablet taken 3 times daily for 6 days prior to exposure to diesel exhaust for 2 hours. The last supplement was taken the morning of the exposure
Experimental: Diesel exhaust with N-acetylcysteine
Exposure for 2 hours to diesel exhaust and N-acetylcysteine tablets (600 mg) 3 times daily for 6 days
Other: Diesel exhaust
A placebo tablet taken 3 times daily for 6 days prior to exposure to diesel exhaust for 2 hours. The last supplement was taken the morning of the exposure
Dietary supplement: N-acetylcysteine
N-acetylcysteine 600mg taken orally 3 times daily for 6 days prior to exposure to diesel exhaust for 2 hours. The last supplement was taken the morning of the exposure

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Human airway reactivity
Time Frame: 50 hours
Establish that oxidative stress is responsible for changes in human airway reactivity induced by DE (300 µg/m3 inhaled for two hours).
50 hours

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of British Columbia

Investigators

  • Principal Investigator: Christopher Carlsten, MD MPH, University of British Columbia

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

September 1, 2007

Primary Completion (Actual)

October 1, 2011

Study Completion (Actual)

October 1, 2011

Study Registration Dates

First Submitted

October 1, 2012

First Submitted That Met QC Criteria

October 1, 2012

First Posted (Estimate)

October 3, 2012

Study Record Updates

Last Update Posted (Actual)

September 29, 2017

Last Update Submitted That Met QC Criteria

September 27, 2017

Last Verified

September 1, 2017

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • H08-02288

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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